COVID-19 vaccine mRNA not found in breast milk

Editor's Note

In this study, researchers from the University of California, San Francisco, found no vaccine-associated mRNA—the active components of the Moderna and Pfizer vaccines—in breast milk samples collected 4 to 48 hours after COVID-19 vaccinations.

Thirteen breast milk samples were collected from 7 breastfeeding women before vaccination and at varied time points 4 to 48 hours after vaccination.

None of the samples showed detectable levels of vaccine mRNA in any component of the milk.

The findings provide important evidence to strengthen current recommendations that vaccine-related mRNA is not transferred to the infant and that lactating women who receive an mRNA based vaccine should not stop breastfeeding.

Data from larger populations are needed to better estimate the effect of these vaccines on lactation outcomes, the researchers say.